Abstract

Worldwide, seagrasses face threats including climate change, disease and anthropogenic disturbance, with populations at the extremes of species' distributions likely presaging future problems elsewhere in their geographical ranges. At the geographic limits of two marine macrophytes (Zostera marina and Posidonia oceanica) and under intense urbanization, seagrasses around Gibraltar are particularly vulnerable. However, the last published survey of Gibraltar seagrass meadows, in 1993, showed both species were abundant. We resurveyed this area and were unable to locate any seagrass in Gibraltar waters. Extensive coastal development and land reclamation make much former seagrass habitat in Gibraltar waters unsuitable, presenting substantial hurdles to any future restoration efforts.